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💻AP Computer Science A
Key Terms

948 essential vocabulary terms and definitions to know for your AP Computer Science A exam

Study AP Computer Science A
Practice Vocabulary
💻AP Computer Science A
Key Terms by Unit

💻Unit 1 – Using Objects and Methods

TermDefinition
booleanA primitive data type that holds one of two values: true or false.
Boolean valueData values that can only be true or false, used in logical operations and conditional statements.
data typeA classification that specifies what kind of value a variable can store and what operations can be performed on it.
doubleA primitive data type used to store real numbers (numbers with decimal points).
intA primitive data type used to store integer values (whole numbers).
primitive data typeBasic data types in Java such as int, double, boolean, and char that are not objects.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
arithmetic expressionMathematical expressions consisting of numeric values, variables, and operators that perform calculations.
castingThe process of converting a value from one primitive data type to another, such as from double to int or int to double.
casting operatorOperators used to convert a value from one data type to another, such as converting a double to an int.
data typeA classification that specifies what kind of value a variable can store and what operations can be performed on it.
doubleA primitive data type used to store real numbers (numbers with decimal points).
intA primitive data type used to store integer values (whole numbers).
integer expressionA mathematical or computational expression that evaluates to an integer value.
integer overflowAn error that occurs when an integer expression evaluates to a value outside the allowed range for the int data type, resulting in an unexpected value.
Integer.MAX_VALUEA Java constant that holds the largest possible value that can be stored in an int variable.
Integer.MIN_VALUEA Java constant that holds the smallest possible value that can be stored in an int variable.
out of rangeA value that exceeds the maximum or minimum limits allowed for a particular data type.
precisionThe degree of exactness with which a floating-point number can be represented in computer memory.
primitive data typeBasic data types in Java such as int, double, boolean, and char that are not objects.
round-off errorAn error that occurs when a computed value cannot be exactly represented in the available memory and must be rounded to the nearest representable value.
roundingThe process of converting a decimal number to the nearest integer value.
truncationThe removal of digits to the right of the decimal point when casting a double value to an int value.
wideningThe automatic conversion of a value from a smaller primitive type (like int) to a larger primitive type (like double).

TermDefinition
APIAn application programming interface that provides a specification informing programmers how to use classes and libraries.
attributeThe data or properties that define the state of an object or class.
behaviorThe methods or actions that an object or class can perform.
classA formal implementation or blueprint that defines the attributes and behaviors of objects.
libraryCollections of classes that can be utilized to create objects and are documented in API specifications.
methodA named block of code that only runs when it is called, allowing programmers to reuse code and organize programs into logical sections.
objectA specific instance of a class with defined attributes and behaviors.
packageOrganizational groupings of classes within APIs and libraries.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.

TermDefinition
additionThe arithmetic operator (+) that combines two numeric values to produce their sum.
arithmetic expressionMathematical expressions consisting of numeric values, variables, and operators that perform calculations.
ArithmeticExceptionAn exception that occurs when attempting to divide an integer by zero.
compound expressionExpressions that use multiple operators to combine numeric values.
divisionThe arithmetic operator (/) that divides one numeric value by another.
doubleA primitive data type used to store real numbers (numbers with decimal points).
escape sequenceA special sequence of characters starting with a backslash that has a special meaning in Java, such as \" for double quote, \\ for backslash, and \n for newline.
intA primitive data type used to store integer values (whole numbers).
integer divisionDivision of two int values that results in only the integer portion of the quotient, discarding any fractional part.
literalThe code representation of a fixed value.
multiplicationThe arithmetic operator (*) that produces the product of two numeric values.
numeric valueNumbers used in expressions, which can be of type int or double.
operatorSymbols that perform operations on numeric values in expressions.
operator precedenceThe rules that determine the order in which operators are evaluated in an expression, with multiplication, division, and remainder evaluated before addition and subtraction.
parenthesesSymbols used to modify operator precedence and control the order of operations in an expression.
remainder operatorThe operator (%) that computes the remainder when one number is divided by another.
string literalA sequence of characters enclosed in double quotes used to create a String object directly in code.
subtractionThe arithmetic operator (-) that finds the difference between two numeric values.
System.out.printA Java method that displays information on the computer display without moving the cursor to a new line after the output.
System.out.printlnA Java method that displays information on the computer display and moves the cursor to a new line after the output.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
call by valueA method of passing arguments where the parameters are initialized with copies of the argument values rather than references to the original values.
constructorA special method that is called to create and initialize an object of a class, having the same name as the class.
constructor argumentA value passed to a constructor when it is called that must match the type, order, and number of parameters in the constructor signature.
constructor signatureThe combination of a constructor's name (same as the class name) and its ordered list of parameter types that uniquely identifies the constructor.
flow of controlThe order in which statements in a program are executed, which can be interrupted by method calls and resumed after the method completes.
newA Java keyword used to create a new instance of a class by allocating memory and calling the constructor.
nullA special value indicating that a reference variable does not currently reference any object.
objectA specific instance of a class with defined attributes and behaviors.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
overloaded constructorMultiple constructors in the same class that have different signatures, allowing objects to be created with different sets of parameters.
parameterA variable declared in the header of a method or constructor that receives values passed to the method when it is called.
parameter typesThe data types of the values that are passed to a constructor or method.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

TermDefinition
dot operatorThe symbol (.) used in Java to access instance methods and properties of an object.
instance methodsMethods that belong to an object and are called on specific instances of a class using the dot operator.
null referenceA reference variable that points to no object, which will cause a NullPointerException if an instance method is called on it.
NullPointerExceptionAn exception that occurs when a method is called on a null reference instead of a valid object.

TermDefinition
class methodsMethods that are associated with a class rather than with instances of the class, and include the static keyword in their header.
dot operatorThe symbol (.) used in Java to access instance methods and properties of an object.
staticA keyword used in a method header to indicate that the method is a class method associated with the class itself, not with individual instances.

TermDefinition
abs()A Math class method that returns the absolute value of a numeric parameter.
built-in mathematical librariesPre-written code libraries in Java that contain mathematical functions and methods available for use without needing to write them from scratch.
casting operatorOperators used to convert a value from one data type to another, such as converting a double to an int.
class methodsMethods that are associated with a class rather than with instances of the class, and include the static keyword in their header.
exclusive endpointAn endpoint of a range where the boundary value is not included in the possible results.
inclusive endpointAn endpoint of a range where the boundary value is included in the possible results.
java.lang packageA Java package containing fundamental classes that are automatically available without explicit import statements.
Math classA Java class in the java.lang package that contains static methods for performing mathematical operations.
pow()A Math class method that returns the value of the first parameter raised to the power of the second parameter.
random()A Math class method that returns a random double value greater than or equal to 0.0 and less than 1.0.
sqrt()A Math class method that returns the nonnegative square root of a double value.

TermDefinition
compareTo() methodA String method that compares two strings alphabetically and returns a negative value if the first string is less than the second, zero if they are equal, or a positive value if the first string is greater than the second.
concatenationThe process of combining two or more String objects or a String with a primitive value using the + or += operator to create a new String object.
equals methodA String method that returns true if the string contains the same sequence of characters as another string, and false otherwise.
immutableA property of String objects meaning that once created, their content cannot be changed; methods called on a String return a new String rather than modifying the original.
implicit conversionThe automatic conversion of a primitive value to a String object when concatenated with a String.
indexA numeric position in a string, starting from 0 for the first character and going up to one less than the length of the string.
indexOf() methodA String method that returns the index of the first occurrence of a specified substring, or -1 if the substring is not found.
java.lang packageA Java package containing fundamental classes that are automatically available without explicit import statements.
length() methodA String method that returns the number of characters in a String object as an integer.
method overridingWhen a public method in a subclass has the same method signature as a public method in the superclass but with subclass-specific behavior.
Object classThe superclass in Java from which all classes inherit, guaranteeing the existence of the toString method.
String class constructorA method that creates a new String object by calling the String class constructor.
string literalA sequence of characters enclosed in double quotes used to create a String object directly in code.
String objectAn instance of the String class in Java that represents a sequence of characters.
StringIndexOutOfBoundsExceptionAn exception thrown when attempting to access a string index that is outside the valid range of 0 to length - 1.
substring() methodA String method that returns a portion of a string, either from a starting index to an ending index, or from a starting index to the end of the string.
toString methodA method that returns a string representation of an object, automatically called when an object is concatenated with a String.

TermDefinition
argumentA value or variable passed to a method or constructor when it is called.
call by valueA method of passing arguments where the parameters are initialized with copies of the argument values rather than references to the original values.
constructorA special method that is called to create and initialize an object of a class, having the same name as the class.
flow of controlThe order in which statements in a program are executed, which can be interrupted by method calls and resumed after the method completes.
methodA named block of code that only runs when it is called, allowing programmers to reuse code and organize programs into logical sections.
method callAn invocation of a method that interrupts sequential execution and causes the program to execute the method's statements before returning control to the calling location.
method signatureThe combination of a method's name and its ordered list of parameter types, used to identify and call a specific method.
non-void methodA method that returns a value of a specified type that can be stored in a variable or used as part of an expression.
overloaded methodMultiple methods with the same name but different method signatures, allowing the same method name to be used with different parameter types or numbers.
parameterA variable declared in the header of a method or constructor that receives values passed to the method when it is called.
parameter listThe list of parameters in a method signature that specifies the types and order of arguments the method expects.
procedural abstractionThe ability to use a method by knowing what it does without needing to understand how it was implemented.
return statementA statement that terminates method execution and returns control flow to the point immediately following where the method was called.
return valueThe value produced by a non-void method that matches the return type specified in the method header.
void methodA method that does not return a value and cannot be used as part of an expression.

TermDefinition
assignment statementA statement that stores a value in a variable using the assignment operator or a compound assignment operator.
compound assignment operatorOperators (+=, -=, *=, /=, %) that perform an arithmetic operation and assign the result to a variable in a single statement.
post-decrement operatorThe -- operator used after a variable to subtract 1 from its stored value and assign the new value to the variable.
post-increment operatorThe ++ operator used after a variable to add 1 to its stored value and assign the new value to the variable.

TermDefinition
API documentationDocumentation generated from Javadoc comments that describes the functionality and usage of code.
block commentComments in Java denoted by /* */ that span multiple lines or create a block of explanatory text.
commentExplanatory text in code that describes functionality and is ignored by the compiler during program execution.
Javadoc commentComments in Java denoted by /** */ that are used to generate API documentation.
line commentComments in Java denoted by // that apply to a single line of code.
postconditionA condition that must always be true after a method executes, describing the outcome in terms of return values or object attributes.
preconditionA condition that must be true immediately before a method executes in order for the method to behave as expected.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
code compilationThe process of translating source code written by a programmer into machine-readable instructions that a computer can execute.
code executionThe process of running compiled code on a computer to perform the instructions specified in the program.
compilerA program that translates source code into machine code and checks for errors that must be fixed before the program can run.
compiler errorErrors in source code that are detected by a compiler and must be fixed before a program can be executed.
exceptionA type of run-time error that occurs as a result of an unexpected error not detected by the compiler and interrupts the normal flow of program execution.
integrated development environmentA software application that provides comprehensive tools for writing, compiling, and running code in one unified interface.
logic errorA mistake in the algorithm or program that causes it to behave incorrectly or unexpectedly, detected through testing with specific data.
patternRecurring sequences or structures found in everyday processes that can be represented and analyzed.
run-time errorA mistake in the program that occurs during execution and typically causes the program to terminate abnormally.
sequencingThe order in which steps in a process are completed, with steps executed one at a time.
syntax errorA mistake in a program where the rules of the programming language are not followed, detected by the compiler.
text editorA software tool used to write and edit source code in plain text format.

TermDefinition
attributeThe data or properties that define the state of an object or class.
behaviorThe methods or actions that an object or class can perform.
classA formal implementation or blueprint that defines the attributes and behaviors of objects.
inheritanceA relationship in which a subclass draws upon and reuses the attributes and behaviors of a superclass.
instanceA specific occurrence or realization of a class with its own set of attribute values.
memory addressThe location in computer memory where an object is stored, which is referenced by a reference type variable.
objectA specific instance of a class with defined attributes and behaviors.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
subclassA class that extends a superclass and inherits its attributes and behaviors.
superclassA class that contains common attributes and behaviors shared by multiple related classes.

TermDefinition
assignment operatorThe = symbol that allows a program to store the value of an expression on the right into a variable on the left.
assignment statementA statement that stores a value in a variable using the assignment operator or a compound assignment operator.
data typeA classification that specifies what kind of value a variable can store and what operations can be performed on it.
expressionA combination of values, variables, and operators that is evaluated to produce a single value.
initializationThe first assignment of a value to a variable.
inputData or information provided to a program, which can come from various sources such as keyboard, files, or user interactions.
nullA special value indicating that a reference variable does not currently reference any object.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
Scanner classA Java class used to obtain and parse text input from the keyboard or other input sources.
text inputData entered by a user in the form of characters and strings, typically from a keyboard.
variableA named storage location in a program that holds a value of a specific data type; the value can change while the program is running.

🔀Unit 2 – Selection and Iteration

TermDefinition
Boolean expressionAn expression that evaluates to either true or false, used to control the execution of loops and conditional statements.
Boolean valueData values that can only be true or false, used in logical operations and conditional statements.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
primitive data typeBasic data types in Java such as int, double, boolean, and char that are not objects.
reference typeA data type that holds a reference (memory address) to an object rather than storing the object's value directly.
relational operatorOperators used to compare values, including ==, !=, <, >, <=, and >=.

TermDefinition
Boolean expressionAn expression that evaluates to either true or false, used to control the execution of loops and conditional statements.
for loopA type of iterative statement that repeats a block of code a specified number of times using initialization, a Boolean expression, and an update statement.
initializationThe first assignment of a value to a variable.
iteration statementA control structure that repeats a block of code multiple times based on a condition.
loop bodyThe segment of code that is repeated within an iteration statement.
loop control variableThe variable initialized in a for loop that is used to control the number of iterations.
updateThe part of a for loop header that modifies the loop control variable after each iteration of the loop body.
while loopAn iterative statement that repeatedly executes a block of code as long as a specified Boolean expression evaluates to true.

TermDefinition
iteration statementA control structure that repeats a block of code multiple times based on a condition.
run-timeThe period during which a program is executing or running.
statement execution countThe number of times a statement is executed during the running of a program.
tracingThe process of manually following the execution of a program step-by-step to understand how statements are executed.

TermDefinition
Boolean expressionAn expression that evaluates to either true or false, used to control the execution of loops and conditional statements.
flow of controlThe order in which statements in a program are executed, which can be interrupted by method calls and resumed after the method completes.
infinite loopA loop that never terminates because the Boolean expression always evaluates to true.
iterationA form of repetition in which code is executed zero or more times based on a condition.
iteration statementA control structure that repeats a block of code multiple times based on a condition.
iterative processA process that repeats a segment of code multiple times to achieve a desired result.
loop bodyThe segment of code that is repeated within an iteration statement.
off by one errorAn error that occurs when an iteration statement loops one time too many or one time too few.
while loopAn iterative statement that repeatedly executes a block of code as long as a specified Boolean expression evaluates to true.

TermDefinition
inner loopThe iteration statement contained within the body of another iteration statement that executes completely for each iteration of the outer loop.
iteration statementA control structure that repeats a block of code multiple times based on a condition.
nested iterationIteration statements that appear within the body of another iteration statement, where the inner loop completes all its iterations before the outer loop advances to its next iteration.
outer loopThe iteration statement that contains another iteration statement within its body.

TermDefinition
character reversalThe process of rearranging the characters in a string in reverse order, from last to first.
string algorithmProcedures or methods designed to perform operations on strings, such as searching, modifying, or analyzing text data.
substringContiguous sequences of characters within a larger string.

TermDefinition
! (not)A logical operator that negates a Boolean expression, returning true if the expression is false and false if the expression is true.
&& (and)A logical operator that returns true only when both Boolean expressions are true, and false otherwise.
|| (or)A logical operator that returns true when at least one of the Boolean expressions is true, and false only when both are false.
compound Boolean expressionBoolean expressions that combine multiple Boolean values or conditions using logical operators to produce a single Boolean result.
logical operatorSymbols or keywords used to combine or modify Boolean expressions: ! (not), && (and), and || (or).
order of precedenceThe sequence in which logical operators are evaluated in an expression: ! (not) first, && (and) second, then || (or).
short-circuit evaluationAn optimization where a logical operation using && or || stops evaluating as soon as the final result can be determined, without evaluating all expressions.

TermDefinition
Boolean expressionAn expression that evaluates to either true or false, used to control the execution of loops and conditional statements.
branching logical processProgram flow that divides into different paths based on conditional statements, allowing different code to execute depending on whether conditions are true or false.
if-else-ifA conditional statement structure that tests multiple conditions in sequence, executing the code block for the first condition that evaluates to true.
multiway selectionA control structure using if-else-if statements to choose one of several code segments to execute based on different conditions.
nested if statementIf, if-else, or if-else-if statements placed within other if, if-else, or if-else-if statements to create multiple levels of conditional branching.

TermDefinition
Boolean expressionAn expression that evaluates to either true or false, used to control the execution of loops and conditional statements.
branching logical processProgram flow that divides into different paths based on conditional statements, allowing different code to execute depending on whether conditions are true or false.
flow of controlThe order in which statements in a program are executed, which can be interrupted by method calls and resumed after the method completes.
if statementA selection statement that executes a code segment based on whether a Boolean expression is true or false.
if-else statementA selection statement that provides two alternative code segments: one executed when a Boolean expression is true and another when it is false.
one-way selectionAn if statement that executes a code segment only when a Boolean expression is true.
selection statementProgramming statements that control the flow of execution by choosing which code segments to run based on conditions.
sequential executionThe default flow of a program where statements are executed one after another in the order they appear.
two-way selectionAn if-else statement that executes one code segment when a Boolean expression is true and a different segment when it is false.

TermDefinition
!=The not-equal operator used to determine if two object references are different or if a reference does not equal a value.
==The equality operator used to compare object references or values; for objects, it checks if two variables reference the same object in memory.
Boolean expressionAn expression that evaluates to either true or false, used to control the execution of loops and conditional statements.
De Morgan's lawA logical rule that allows conversion between equivalent Boolean expressions: !(a && b) is equivalent to !a || !b, and !(a || b) is equivalent to !a && !b.
equals methodA String method that returns true if the string contains the same sequence of characters as another string, and false otherwise.
equivalencyThe state of two objects being equal based on specified criteria, typically determined by comparing their attributes.
equivalentHaving the same value or producing the same result; two Boolean expressions are equivalent if they evaluate to the same value in all cases.
nullA special value indicating that a reference variable does not currently reference any object.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
truth tableA table that shows all possible input combinations and their corresponding output values, used to prove whether Boolean expressions are equivalent.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
decision makingThe process in an algorithm where a choice is made based on evaluating a condition to determine which path to follow.
loopingA programming construct that repeats a block of code multiple times as part of an algorithm's repetition.
repetitionA control structure in an algorithm where a process repeats itself until a desired outcome is reached.
selectionA control structure in an algorithm that makes a choice about how execution will proceed based on a true or false decision.
sequencingThe order in which steps in a process are completed, with steps executed one at a time.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
averageThe mean value calculated by dividing the sum of all values by the number of values.
evenly divisibleA property of an integer that can be divided by another integer with no remainder.
frequencyThe number of times a specific criterion or condition is met within a dataset or sequence.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
standard algorithmA widely recognized, established procedure for solving a common computational problem.
sumThe result of adding multiple values together.

🏗️Unit 3 – Class Creation

TermDefinition
accessor methodA non-void method that allows objects of other classes to obtain a copy of the value of instance variables or class variables.
class variableVariables that belong to the class itself rather than individual objects and can be accessed or modified by accessor and mutator methods.
instance variableA variable that belongs to an object and can be accessed throughout the class, as opposed to a local variable that is limited to a specific block of code.
mutator methodA method that changes the values of instance variables or class variables, often implemented as a void method.
non-void methodA method that returns a value of a specified type that can be stored in a variable or used as part of an expression.
parametersVariables that allow procedures to be generalized and reused with a range of input values or arguments.
primitive valuesBasic data types in Java such as int, double, and boolean that store actual values directly.
return by valueThe process in which a non-void method evaluates a return expression compatible with the return type and returns that value.
return statementA statement that terminates method execution and returns control flow to the point immediately following where the method was called.
return typeThe data type of the value that a non-void method returns, specified in the method header.
void methodA method that does not return a value and cannot be used as part of an expression.

TermDefinition
class methodsMethods that are associated with a class rather than with instances of the class, and include the static keyword in their header.
class variableVariables that belong to the class itself rather than individual objects and can be accessed or modified by accessor and mutator methods.
dot operatorThe symbol (.) used in Java to access instance methods and properties of an object.
final keywordA Java keyword that, when applied to a variable, prevents its value from being modified after initialization.
instance methodsMethods that belong to an object and are called on specific instances of a class using the dot operator.
instance variableA variable that belongs to an object and can be accessed throughout the class, as opposed to a local variable that is limited to a specific block of code.
parameterA variable declared in the header of a method or constructor that receives values passed to the method when it is called.
public access modifierA keyword that allows class variables to be accessed outside of the class using the class name and dot operator.
static keywordA Java keyword used to designate that a variable belongs to the class rather than to individual objects of the class.

TermDefinition
class methodA method that belongs to the class itself rather than to individual instances and does not have access to a this reference.
constructorA special method that is called to create and initialize an object of a class, having the same name as the class.
current objectThe specific object instance whose method or constructor is being executed.
instance methodA method that belongs to an object instance and can access and modify the instance's data through the this keyword.
method callAn invocation of a method that interrupts sequential execution and causes the program to execute the method's statements before returning control to the calling location.
self-referencingCode that refers to the current object using the this keyword.
this keywordA special variable that holds a reference to the current object within an instance method or constructor.

TermDefinition
attributeThe data or properties that define the state of an object or class.
constructorA special method that is called to create and initialize an object of a class, having the same name as the class.
constructor parametersData passed to a constructor that is used to initialize instance variables with specific values.
default constructorA no-parameter constructor automatically provided by Java when no constructor is explicitly written; initializes instance variables to default values.
default valuesThe initial values automatically assigned to instance variables by the default constructor based on their data type (0 for int, 0.0 for double, false for boolean, null for reference types).
has-a relationshipA relationship between an object and its instance variables, indicating that an object has certain attributes.
instance variableA variable that belongs to an object and can be accessed throughout the class, as opposed to a local variable that is limited to a specific block of code.
mutable objectAn object whose state can be changed after it is created; when used as a constructor parameter, a copy should be made to prevent external modification.
object's stateThe current values of all instance variables belonging to an object at a given time.

TermDefinition
abstractionThe process of reducing complexity by focusing on main ideas and hiding irrelevant details while bringing together related and useful details.
attributeThe data or properties that define the state of an object or class.
classA formal implementation or blueprint that defines the attributes and behaviors of objects.
class variableVariables that belong to the class itself rather than individual objects and can be accessed or modified by accessor and mutator methods.
code reuseThe practice of using existing methods and procedural abstractions multiple times rather than duplicating code, which helps manage complexity.
data abstractionA separation between the abstract properties of a data type and the concrete details of its representation, allowing data to be named without referencing specific implementation details.
instance variableA variable that belongs to an object and can be accessed throughout the class, as opposed to a local variable that is limited to a specific block of code.
methodA named block of code that only runs when it is called, allowing programmers to reuse code and organize programs into logical sections.
method decompositionThe process of breaking down larger behaviors of a class into smaller behaviors by creating individual methods to represent each smaller behavior.
method signatureThe combination of a method's name and its ordered list of parameter types, used to identify and call a specific method.
parametersVariables that allow procedures to be generalized and reused with a range of input values or arguments.
procedural abstractionThe ability to use a method by knowing what it does without needing to understand how it was implemented.

TermDefinition
access constraintsRestrictions that control which classes and methods can access or modify a class, data, constructors, or methods.
attributeThe data or properties that define the state of an object or class.
behaviorThe methods or actions that an object or class can perform.
constructorsSpecial methods used to initialize objects of a class, typically designated as public in this course.
data encapsulationA technique in which the implementation details of a class are kept hidden from external classes to protect internal structure and behavior.
instance variableA variable that belongs to an object and can be accessed throughout the class, as opposed to a local variable that is limited to a specific block of code.
methodA named block of code that only runs when it is called, allowing programmers to reuse code and organize programs into logical sections.
privateA keyword that restricts access to a class, data, constructor, or method to only the declaring class.
publicA keyword that allows access to a class, data, constructor, or method from classes outside the declaring class.
visibility constraintsSpecifications that determine whether classes, data, constructors, and methods are visible and accessible to external classes.

TermDefinition
block of codeA section of code enclosed in braces that defines a region where variables can be declared and accessed.
instance variableA variable that belongs to an object and can be accessed throughout the class, as opposed to a local variable that is limited to a specific block of code.
local variablesVariables declared in the headers or bodies of blocks of code that can only be accessed within the block in which they are declared.
parametersVariables that allow procedures to be generalized and reused with a range of input values or arguments.
scopeThe region of code in which a variable can be accessed and used.

TermDefinition
enclosing classThe class in which a method is defined.
mutable objectAn object whose state can be changed after it is created; when used as a constructor parameter, a copy should be made to prevent external modification.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
parameterA variable declared in the header of a method or constructor that receives values passed to the method when it is called.
private dataClass members declared with the private access modifier that can only be accessed within the same class.
return expressionThe value or reference that a method sends back to the code that called it.

TermDefinition
ethical implicationsThe moral and ethical consequences of computing systems, including questions about right and wrong in their design and use.
intellectual propertyLegal rights and protections for original creative works, including software code and programs.
open sourceSoftware code that is publicly available and free to use, modify, and distribute without requiring permission or payment.
social implicationsThe effects and consequences of computing systems on society, including how they impact people's lives and social structures.
system reliabilityThe ability of a program to perform its intended tasks as expected under stated conditions without failure.

📚Unit 4 – Data Collections

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
averageThe mean value calculated by dividing the sum of all values by the number of values.
delete elementsThe operation of removing elements from a collection.
duplicate elementsMultiple occurrences of the same value within a collection.
insert elementsThe operation of adding new elements into a collection at a specified position.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
reverseTo arrange elements in an array in the opposite order from their original sequence.
rotate elementsTo move elements in an array circularly so that elements shifted off one end reappear at the other end.
shift elementsTo move all elements in an array left or right by one or more positions.
sumThe result of adding multiple values together.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
array traversalThe process of using repetition statements to systematically access elements in an array.
averageThe mean value calculated by dividing the sum of all values by the number of values.
consecutive pairsTwo adjacent elements in an array that are next to each other in sequence.
duplicate elementsMultiple occurrences of the same value within a collection.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
reverseTo arrange elements in an array in the opposite order from their original sequence.
rotate elementsTo move elements in an array circularly so that elements shifted off one end reappear at the other end.
shift elementsTo move all elements in an array left or right by one or more positions.
sumThe result of adding multiple values together.

TermDefinition
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
averageThe mean value calculated by dividing the sum of all values by the number of values.
consecutive pairsTwo adjacent elements in an array that are next to each other in sequence.
duplicate elementsMultiple occurrences of the same value within a collection.
maximum valueThe largest value in a set of data or collection of numbers.
minimum valueThe smallest value in a set of data or collection of numbers.
reverseTo arrange elements in an array in the opposite order from their original sequence.
rotate elementsTo move elements in an array circularly so that elements shifted off one end reappear at the other end.
shift elementsTo move all elements in an array left or right by one or more positions.
sumThe result of adding multiple values together.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
ArrayIndexOutOfBoundsExceptionAn error that occurs when attempting to access an array element using an index value outside the valid range of 0 through length minus one.
arrays of arraysA data structure where a 2D array is implemented as an array where each element is itself a 1D array.
column indexThe second index in the square brackets [row][col] notation used to specify which column of a 2D array to access.
default valuesThe initial values automatically assigned to instance variables by the default constructor based on their data type (0 for int, 0.0 for double, false for boolean, null for reference types).
initializer listA syntax used to create and initialize an array with specific values at the time of creation.
length attributeA property of an array that indicates the number of elements it contains and cannot be changed after creation.
object reference dataData types that store references to objects rather than primitive values.
primitive dataBasic data types in Java such as int, double, and boolean that store values directly.
row indexThe first index in the square brackets [row][col] notation used to specify which row of a 2D array to access.

TermDefinition
1D arrayAn array with a single row of elements, organized in a linear sequence and accessed using a single index.
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
arrays of arraysA data structure where a 2D array is implemented as an array where each element is itself a 1D array.
column-major orderA traversal pattern of a 2D array where elements are accessed down each column from top to bottom before moving to the next column.
enhanced for loopA Java loop construct that iterates through all elements of a collection without using an index variable.
nested iteration statementsLoop structures where one loop is placed inside another, used to access all elements in a 2D array.
row-major orderA traversal pattern of a 2D array where elements are accessed across each row from left to right before moving to the next row.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
1D arrayAn array with a single row of elements, organized in a linear sequence and accessed using a single index.
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayIndexOutOfBoundsExceptionAn error that occurs when attempting to access an array element using an index value outside the valid range of 0 through length minus one.
default valuesThe initial values automatically assigned to instance variables by the default constructor based on their data type (0 for int, 0.0 for double, false for boolean, null for reference types).
indexA numeric position in a string, starting from 0 for the first character and going up to one less than the length of the string.
initializer listA syntax used to create and initialize an array with specific values at the time of creation.
length attributeA property of an array that indicates the number of elements it contains and cannot be changed after creation.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
primitive valuesBasic data types in Java such as int, double, and boolean that store actual values directly.

TermDefinition
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
ArrayList objectsResizable collections in Java that can dynamically grow or shrink and can be traversed recursively.
binary search algorithmA search algorithm that finds a target value in a sorted collection by repeatedly dividing the search space in half, eliminating half of the remaining elements with each iteration.
iterationA form of repetition in which code is executed zero or more times based on a condition.
iterativelyA method of solving a problem by repeating a set of instructions in a loop rather than through recursive function calls.
linear searchA search algorithm that examines each element in a collection sequentially from the beginning until the target value is found or the end is reached.
merge sortA recursive sorting algorithm that divides an array into smaller subarrays, sorts them, and then merges them back together in sorted order.
recursionA programming technique where a function calls itself to solve a problem by breaking it into smaller, similar subproblems.
recursive algorithmsAlgorithms that solve problems by having a function call itself with modified parameters until reaching a base case.
recursive callAn instance where a method invokes itself as part of its execution.
recursive sorting algorithmA sorting algorithm that uses recursion to divide and organize elements in a collection.
recursivelyA method of solving a problem by having a function call itself with modified parameters until a base case is reached.
sorted orderA requirement for binary search in which elements in a collection are arranged in a specific sequence, typically in ascending or descending order.
String objectsData structures in Java that represent sequences of characters and can be traversed recursively.
subarrayA contiguous portion of an array.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
add(E obj) methodAn ArrayList method that appends an object to the end of the list and returns true.
add(int index, E obj) methodAn ArrayList method that inserts an object at a specified position and shifts elements to the right.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
generic typeA parameterized type that specifies the data type of elements a collection will contain, such as ArrayList<E>.
get(int index) methodAn ArrayList method that returns the element at a specified position in the list.
import statementA Java statement used to make classes from a package available for use in a program.
indexA numeric position in a string, starting from 0 for the first character and going up to one less than the length of the string.
java.util packageA Java library package that contains utility classes including ArrayList.
mutableCapable of being changed or modified after creation, such as an ArrayList that can grow or shrink in size.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
remove(int index) methodAn ArrayList method that removes the element at a specified position and shifts elements to the left.
set(int index, E obj) methodAn ArrayList method that replaces the element at a specified position and returns the former element.
size() methodAn ArrayList method that returns the number of elements currently in the list.
type parameterA placeholder for a specific data type in a generic class, represented by E in ArrayList<E>.

TermDefinition
close()A Scanner method that closes the scanner and the associated file when the program is finished using it.
fileA storage location for data that persists when a program is not running and can be retrieved during program execution.
File classA Java class used to create a File object that connects a program to a text file for reading data.
hasNext()A Scanner method that returns true if there is another item to read in the file or input source, and false otherwise.
import statementA Java statement used to make classes from a package available for use in a program.
InputMismatchExceptionAn exception thrown when a Scanner method attempts to read a value that does not match the expected data type or is out of range.
IOExceptionAn exception class that is thrown when a file cannot be opened or read due to an invalid file name or I/O error.
java.io packageA Java package containing classes like File and IOException that must be imported to use file input/output operations.
next()A Scanner method that returns the next String token read from a file or input source.
nextBoolean()A Scanner method that returns the next boolean value read from a file or input source.
nextDouble()A Scanner method that returns the next double value read from a file or input source.
nextInt()A Scanner method that returns the next integer value read from a file or input source.
nextLine()A Scanner method that returns the next line of text as a String read from a file or input source.
Scanner classA Java class used to obtain and parse text input from the keyboard or other input sources.
split()A String method that returns a String array by dividing a String into substrings based on a given delimiter expression.
throws IOExceptionA method declaration clause that indicates the method may throw an IOException if a file cannot be opened.
while loopAn iterative statement that repeatedly executes a block of code as long as a specified Boolean expression evaluates to true.
whitespaceBlank characters such as spaces, tabs, and newlines that Scanner methods handle differently when reading from a file.

TermDefinition
base caseA condition in a recursive method that stops the recursion and prevents infinite calls.
iterative approachA method of solving a problem using loops and repetition instead of recursion.
local variablesVariables declared in the headers or bodies of blocks of code that can only be accessed within the block in which they are declared.
parametersVariables that allow procedures to be generalized and reused with a range of input values or arguments.
recursive callAn instance where a method invokes itself as part of its execution.
recursive methodA method that calls itself to solve a problem by breaking it down into smaller instances of the same problem.

TermDefinition
algorithmic biasSystemic and repeated errors in a program that create unfair outcomes for a specific group of users.
biasSystematic prejudice or error in data collection or program logic that leads to unfair or inaccurate outcomes.
data collectionThe process of gathering information about individuals through computer systems and other means.
data qualityThe accuracy, completeness, and reliability of data in a dataset, which affects the correctness of programs and conclusions drawn from the data.
data setA collection of related data values that can be analyzed to answer questions or solve problems.
data set collection methodThe process and technique used to gather data for a dataset, which can introduce bias or affect data quality.
data storageThe process of keeping collected personal information on computer systems for later access or use.
inaccurate dataData that contains errors or does not correctly represent the actual values or facts, potentially causing program malfunction.
incomplete dataA dataset that is missing information or records, which can cause programs to work incorrectly or inefficiently.
personal dataInformation about individuals that can be used to identify them or reveal details about their lives, activities, or characteristics.
privacyThe right of individuals to control access to their personal information and have it protected from unauthorized collection, use, or disclosure.
safeguardProtective measures taken to prevent unauthorized access to or misuse of personal data.

TermDefinition
algorithmA step-by-step procedure or set of rules designed to solve a problem or accomplish a task.
chartA visual representation of data used to organize and display information in a way that aids understanding and planning.
data setA collection of related data values that can be analyzed to answer questions or solve problems.
tableA structured visual representation of data organized in rows and columns that can be used to plan algorithms.

TermDefinition
array indexThe numeric position used to access a specific element in an array.
array traversalThe process of using repetition statements to systematically access elements in an array.
enhanced for loopA Java loop construct that iterates through all elements of a collection without using an index variable.
enhanced for loop variableThe variable in an enhanced for loop header that is assigned a copy of each array element during each iteration.
indexed for loopA loop that accesses array elements by using their index positions to control iteration.
object referenceA value that points to the memory location where an object is stored, allowing access to that object.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.
while loopAn iterative statement that repeatedly executes a block of code as long as a specified Boolean expression evaluates to true.

TermDefinition
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
insertion sortAn iterative sorting algorithm that inserts elements from the unsorted portion into their correct position in the sorted portion by shifting elements to make room.
iterative sorting algorithmsSorting algorithms that use repetition to progressively sort elements by performing the same operation multiple times.
selection sortAn iterative sorting algorithm that repeatedly selects the smallest or largest element from the unsorted portion and places it in its correct final position in the sorted portion.
sorted portionThe part of a collection that has been arranged in the desired order during a sorting process.
sorting algorithmsStep-by-step procedures used to arrange elements in a collection in a specific order, such as ascending or descending.
swapThe operation of exchanging the positions of two elements in a collection.
unsorted portionThe part of a collection that has not yet been arranged in the desired order during a sorting process.

TermDefinition
2D arrayA two-dimensional data structure consisting of rows and columns used to store and organize data in a grid format.
arrayA data structure that stores a fixed-size collection of elements of the same type in contiguous memory locations, accessed by index.
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
linear search algorithmsStandard algorithms that check each element in a collection in order until the desired value is found or all elements have been checked.

TermDefinition
ArrayListA resizable array implementation in Java that can dynamically grow or shrink to store a collection of objects.
ConcurrentModificationExceptionAn exception that occurs when the size of an ArrayList is changed while traversing it using an enhanced for loop.
enhanced for loopA Java loop construct that iterates through all elements of a collection without using an index variable.
IndexOutOfBoundsExceptionAn exception that occurs when attempting to access an index value outside the valid range of an ArrayList.
iterationA form of repetition in which code is executed zero or more times based on a condition.
recursive statementsProgramming statements that call themselves to process elements in a data structure.
traverseTo visit each element in a data structure (such as a string, array, or ArrayList) in a systematic way, often using recursion.

TermDefinition
autoboxingThe automatic conversion by the Java compiler from a primitive type to its corresponding wrapper class object, such as converting an int to an Integer or a double to a Double.
Double classA wrapper class in the java.lang package that represents a primitive double value as an object; Double objects are immutable.
immutableA property of String objects meaning that once created, their content cannot be changed; methods called on a String return a new String rather than modifying the original.
Integer classA wrapper class in the java.lang package that represents a primitive int value as an object; Integer objects are immutable.
parseDoubleA static method of the Double class that converts a String argument to a double value.
parseIntA static method of the Integer class that converts a String argument to an int value.
primitive typeA basic data type in Java such as int or double that is not an object.
unboxingThe automatic conversion by the Java compiler from a wrapper class object to its corresponding primitive type, such as converting an Integer to an int or a Double to a double.
wrapper classA class that encapsulates a primitive data type and provides object-oriented functionality, such as Integer and Double.

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